• DerisionConsulting@lemmy.ca
    link
    fedilink
    English
    arrow-up
    7
    ·
    10 months ago

    There isn’t a valid answer to the question.

    Ignore the numbers, and just think about this:
    Is there a number that you can add 2 to, that would equal the same about as if you subtracted 2 from it?
    The answer is no.

    So the person, who is pretending to be smart, just did a bunch of fake math.
    Also √4 = 2, so the “answer” they have is just them trying to re-write the question x + 2 = x - 2.

      • rasensprenger@feddit.de
        link
        fedilink
        English
        arrow-up
        3
        ·
        edit-2
        10 months ago

        The square root of x is usually defined as the positive real number that squares to x, so x^2 = 4 => x = ±2 but sqrt(4) = 2, not ±2

        The complex sqrt function is multivalued, but that opens a whole other can of worms

        • digdug@kbin.social
          link
          fedilink
          arrow-up
          6
          ·
          10 months ago

          And even if you allowed sqrt(4) = ±2, it would still be invalid to evaluate it to -2 on one side of the equation, but then use +2 on the other side.